The piwik.js uses Hardcoded variables for campaignNameParameters and campaignKeywordParameters. See js/piwik.js line 1340, 1341.
It must use the values from from the config file. Or is there any posibility to set these variables?
Does this mean that the variables must be set twice in PHP and JS. This sounds not very convenient and could cause errors. I think there should be something that synchronizes both settings.
There's no way to "sync" the config after the tracking code has been pasted to a web page / template.
But there are tickets for a tracking code wizard and campaign url builder. Those should take into account the server configuration, and present the appropriate output.
I think a simple FAQ would be enough to clarify this. But it's definitely not recommended to customize the parameter name.
Matt: can you follow-up on this: http://forum.piwik.org/read.php?5,75698